What does a "wandering atrial pacemaker" reflect on the EKG?

A wandering atrial pacemaker is characterized by a variation in P wave morphology on the electrocardiogram (EKG). This condition occurs when there is shifting of the primary pacemaker site within the atria. As a result, the P waves can show different shapes and sizes because they originate from different sites in the atrial tissue, reflecting the changing atrial pacemaker location.

In contrast, if the P waves were consistent in morphology, it would indicate that a single atrial pacemaker is dominating the rhythm, which is not the case in wandering atrial pacemaker. The absence of P waves would be indicative of a more severe conduction issue where atrial depolarization does not occur at all, such as in atrial fibrillation or atrial standstill. An increased heart rate is not a defining characteristic of wandering atrial pacemaker; rather, the heart rate can often be normal or slightly elevated, but the hallmark of this condition is the variation in P wave shapes. Therefore, the characteristic of variation in P wave morphology is what correctly describes the wandering atrial pacemaker on an EKG.